The present invention relates to novel cationic lipids that can be used in combination with other lipid components such as cholesterol and PEG-lipids to form lipid nanoparticles with oligonucleotides, to facilitate the cellular uptake and endosomal escape, and to knockdown target mRNA both in vitro and in vivo.
Cationic lipids and the use of cationic lipids in lipid nanoparticles for the delivery of oligonucleotides, in particular siRNA and miRNA, have been previously disclosed. (See US patent applications: US 2006/0008910, US 2006/0083780, US 2006/0240554, US 2008/0020058, US 2009/0263407 and US 2009/0285881 and PCT patent applications: WO 2009/086558, WO 2010/042877, WO 2010/048536, WO 2010/088537, and WO 2009/127060). See also Semple S. C. et al., Rational design of cationic lipids for siRNA delivery, Nature Biotechnology, published online 17 Jan. 2010; doi:10.1038/nbt.1602. Lipid nanoparticles and use of lipid nanoparticles for the delivery of oligonucleotides, in particular siRNA and miRNA, has been previously disclosed. (See US patent applications: US 2006/0240554 and US 2008/0020058). Oligonucleotides (including siRNA and miRNA) and the synthesis of oligonucleotides has been previously disclosed. (See US patent applications: US 2006/0240554 and US 2008/0020058).
Traditional cationic lipids such as DLinDMA have been employed for siRNA delivery to liver but suffer from extended tissue half lives. It is an object of the instant invention to provide a cationic lipid scaffold that is susceptible to hydrolytic instability that may translate into reduced liver residence times and reduced hepatocellular toxicity. The present invention employs acetals and ketals to provide a low pH sensitive chemical handle for degradation.